System, apparatuses, methods, and computer-readable media using identification data in packet communications

ABSTRACT

Methods, systems and computer-readable data storage media for authentication and/or access authorization in a communications network. A source node initiates a request for network services, such as session establishment, database access, or application access. Known network resources, authorized user, and/or source information are stored in a database at a network portal along with access policy rules that can be device and/or user dependent. A source node can construct a packet header including a user identifier indicating the user originating the request, and/or a source identifier indicating the hardware from which the request is originated. At least one of these identifiers are included with a synchronization packet for transmission to a destination node. An appliance or firewall in the communications network receives, authenticates, and determines whether resource access is authorized before releasing the packet to its intended destination.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part under 35 U.S.C. §120 and 37 C.F.R §1.53(b) of U.S. application Ser. No. 10/065,775 filed Nov. 18, 2002 naming as inventor A. David Shay, which is hereby incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to network security. More specifically, the invention relates to a system and method for providing trusted communications and preventing intrusions in computer communications networks from occurring.

[0003] In the current state of the art, the common approach to communications network security is an attempt to identify occurrences of attacker activity after the attacker is present. This requires infrastructure inspections of every packet flow and a state-full inspection at the packet level. After performing all of this work most of these approaches only provide alert messaging of active breaches, thousands of them. Other approaches in security utilize personal encrypted keys and key authentication. These approaches while providing an attempt at session level control carry additional concerns and limitations associated with Quality of Service (QOS) performance impacts along with the need to add additional information to each packet; thus, by looking at the packet, intruders have a clear picture of how and where to modify new packets. In the present context QOS refers to the overall throughput and performance of a network infrastructure. Most corporate security approaches also include anti-viral, signature verification and Network Address Translation (NAT) implementations. NAT enables a local area network to use one set of Internet Protocol (IP) addresses for internal traffic and a second set of addresses for external traffic. Recent attempts have been made to apply flow-based logic to identify hacker activity. However, like their predecessors, these new approaches still rely on “after intrusion” recognition. While improvements have been made to keep up with today's high-speed line rates, intrusion detection is still just that, detection not prevention.

[0004] Network security is of paramount importance to network administrators today. Cyber attacks are becoming more frequent and more publicized. Concerted cyber attacks by terrorist organizations can wreak havoc on the infrastructure that modern societies have come to depend upon. The common methods of attack include network packet sniffing, Internet Protocol (IP) spoofing, password attacks, denial of service attacks and application layer attacks. All of these methods require gaining access to the network and no comprehensive solution exists in the prior art to prevent all forms of network intrusion.

[0005] A current effort to provide secure private communications over the Internet is Internet Protocol Security (IPSec). This framework uses encryption technology to provide confidentiality, integrity and authenticity between peer devices in a private communications network. The IPSec protocol is a set of security extensions to the TCP/IP protocol that uses cryptographic techniques to protect the data in a message packet. The main transformation types are authentication header (AH) transformation and encapsulating security payload (ESP) transformation. AH transformation provides for authentication of the sender of data. ESP transformation provides for authentication of the sender and encryption of data. Both types of transformations can be made in either transport or tunnel mode. Transformation in transport mode means that the original packet IP header will be the IP header for the transformed packet. Transformation in tunnel mode means that the packet is appended after a new IP header. Both AH and ESP transformations add an extra header to the message packet, i.e., an AH header or an ESP header. Separate key protocols can be selected including the Internet key Exchange (IKE). Session keys have to be exchanged between communicating peers in order to provide secure communications. Although IPSec does address certain aspects of network security, it is not a panacea for all types of attacks. The use of an AH transformation does not protect the confidentiality of data; the use of an ESP transformation protects the confidentiality of data, but also requires key exchange, the use of additional headers increasing packet overhead, and the encryption of the actual data payload.

[0006] There is a need for an improved method and system for providing network security that actually prevents intrusions into the network and provides trusted communications between devices in the network.

SUMMARY OF THE INVENTION

[0007] The present invention provides an access control and user session layer security framework. It prevents unwanted connections to new and existing computing resources. It prevents unknown devices and/or users from establishing communication connections to the infrastructure. It prevents unknown devices and/or users from establishing sessions to shared application resources. It prevents known users from gaining access to application resources that are not required in the execution of their area of responsibility.

[0008] Unlike traditional intrusion detection systems, the present invention prevents intrusions rather than simply alerting a network administrator that an intrusion is occurring. The technique used by this invention is the first security approach that links business process to enabled technology utilization; thereby preventing anomalies in access and session establishment. It utilizes authentication through real-time protocol manipulation.

[0009] The invention requires granted authentication at the hardware and user session levels; thus linking hardware access to user requested services. By securing granted permissions at these levels, strange or unknown hardware devices are prevented from communicating with the network infrastructure; thus preventing threats associated with “walk-in” intrusions. Additionally, application resources are secured by controlling where user sessions are allowed; thus preventing “insiders” from gaining access to non-permitted resources and data.

[0010] The invention prevents the initiation of communication establishment through extended manipulation of the communication protocol. This approach places the decision point to the forefront of connection establishment rather than current methods of detecting unwanted “active” utilization or flow. It also eliminates the requirement for “state-full” inspection of every packet associated with end-to-end flows of utilization; thus lowering the performance burden normally associated with intrusion detection.

[0011] The two major components of the invention are a “key master” software component that is added to individual user workstations and network resources, and a “gate keeper” component that can be added to existing firewall devices or operate as a stand alone appliance within a trusted virtual network. The key master software constructs a “transformed” packet header for a synchronization packet before transmitting the packet to a destination node. The gate keeper component is an in-line appliance or software module that intercepts all packet flows associated with a protected trusted virtual network. It processes the initial synchronization packet received from a transmitting node and releases every other packet without further delay. The synchronization packets are inspected to ensure that known hardware and known users are requesting services for network resources that they can access. This inspection is performed by examination of the transformed packet header in the received synchronization packet. Information contained in the synchronization packet is compared to access policy profiles stored in a relational database management system at a network portal. Decisions to permit or reject the request for access to network services are made based on these comparisons. At the receiving end of a connection request, key master software in the receiving node initially identifies packet type and evaluates a packet header field to determine whether to continue processing the packet. Authorization and verification are performed by extracting and transforming data in packet header fields and passing the data to upper protocol layer stack processes. The key master software in the destination node toggles into a conversation mode throughout the rest of the connection until both the originating and destination nodes are informed of the connection's termination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention is better understood by reading the following detailed description of an exemplary embodiment in conjunction with the accompanying drawings, wherein:

[0013]FIG. 1 illustrates a system architecture for implementation of the present invention in accordance with an exemplary embodiment.

[0014]FIG. 2A illustrates the fields and overall format of a TCP packet.

[0015]FIG. 2B illustrates the fields and format of a UDP packet.

[0016]FIG. 3 illustrates a high level view of the major functions in the process flow for the key master and gate keeper intercept software in accordance with an exemplary embodiment of the present invention.

[0017]FIG. 4 illustrates the processing logic associated with requesting network connection services in accordance with an exemplary embodiment of the present invention.

[0018]FIG. 5 illustrates the processing logic associated with the gate keeper authentication process to prevent intrusion in a communications network in accordance with an exemplary embodiment of the present invention.

[0019]FIG. 6 illustrates the processing logic associated with the “perform exception” process in accordance with an exemplary embodiment of the present invention.

[0020]FIG. 7 illustrates the processing logic associated with call setup and response at a destination in accordance with an exemplary embodiment of the present invention.

[0021]FIG. 8 illustrates the processing logic associated with packet flow after a connection is established between two nodes in accordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The following detailed description of the present invention is provided as an enabling teaching of the invention in its best, currently known embodiment. Those skilled in the relevant art will recognize that many changes can be made to the embodiment described, while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without using other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present invention are possible and may even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not in limitation thereof, since the scope of the present invention is defined by the claims.

[0023] The objective of the invention is to prevent intrusion before it occurs by identifying intruders when they try to establish a connection. This new approach not only delivers a preemptive methodology addressing outside intruders but addresses internal intruders as well. Outside intruders are defined as devices originating from the “outside” or off-net who are attempting to connect to resources located within the enterprise infrastructure. Internal intruders are devices connected within the infrastructure that are attempting to connect to unauthorized internal resources.

[0024] Unlike other solutions available today, the invention correlates each request for service with the individual making the request and applies availability rules to the users' identification without tagging or modifying packets. The invention utilizes the normal features of protocol operation and exploits how the protocol works to provide authenticated user level security. This approach delivers a secure method of communications without demanding abnormal construction of packet level data.

[0025] The prevention of unwanted communication is best served by simply not allowing the communication to begin. As an example, when a local telephone company wants to prevent unwanted telephone usage, they simply remove the dial tone. Without receiving a dial tone, a communication circuit cannot be opened. Much like the telephone, computers rely on the closure of a virtual circuit to a destination address or device. By applying intelligent decision making capability at the point of a request, unwanted or unallowable connection closure can be terminated before it begins.

[0026] Resource and delay requirements for this approach will be lower than the traditional approaches as the requirement for continuous state-full inspection of all flow related packets is eliminated. By applying intelligent decision capability at the beginning of a request for connection, only the first few packets must be inspected. The hand-shaking functions of all connection-oriented protocols during initial connection setup provide enough information about the request for service to make the decision whether to acknowledge and allow the connection to be made or to terminate and drop the request. These connection procedures are well-established as Transmission Control Protocol (TCP) under Request for Comments (RFC) 793 promulgated by Defense Advanced Research Projects Agency (DARPA), and other standards. In addition, after a connection is established information held within the first few packets can also be inspected to determine the nature of an acknowledged connection request and to recognize the nature of the user's intent. As an example, denial of service attacks can be identified by evaluating the interaction of the first five packets of the bidirectional flow between two nodes. Once the system of the present invention has recognized that initial interaction as damaging, it can automatically terminate the connection.

[0027] Signature or anti-virus enabled methods of countering virus-based transmissions can be fully supported by including anti-virus enabled software within the system of the invention. This additional feature would be available through direct partnership with anti-virus software vendors such as Network Associates (McAfee security products) or Norton Utilities.

[0028] The following connection scenarios are addressed by the present invention:

[0029] 1. Intercept software-enabled devices connecting to other intercept software-enabled devices.

[0030] 2. Intercept software-enabled devices connecting to non-intercept software-enabled devices.

[0031] 3. Non-intercept software-enabled devices connecting to intercept software-enabled devices.

[0032] 4. Non-intercept software enabled devices connecting to other non-intercept enabled devices.

[0033] Scenario 1 can be described as an internal device connecting to a corporate application host. The origination node requests a connection with an application host that is within the trusted corporate enterprise. The request for connection is routed through the enterprise and is evaluated by the corporate firewall already protecting the data center, if a firewall is present. An intercept software program looks at the connection request and ensures that the device making the request is a known node and the authenticated user has permission to utilize the requested application. Once it has been cleared, the request continues on its way to the host destination. The host destination then responds back to the origination node. Within this response are key indicators that inform the node's intercept software that it has indeed connected to an intercept software-enabled or approved device; thus allowing the continuation of the conversation.

[0034] Scenario 2 can be described as an intercept software-enabled device connecting to a non-intercept software-enabled host. This scenario is applied equally to both internally located hosts and remote hosts. In either case, a “gate keeper” software program evaluates compliance. The originating node request is evaluated by the gate keeper software program implemented as an appliance or running within the firewall, thus ensuring permissions to connect to the selected host are given. The response does not contain the key indicators provided by an intercept software-enabled device. The intercept software running in the workstation recognizes that it has connected to non-intercept software-enabled device and still continues the conversation. Because each original request for connection is first evaluated by the gate keeper software implemented as an appliance or running within protected firewalls, only permitted requests can complete their connections.

[0035] Scenario 3 describes a non-intercept software-enabled device attempting to connect to an intercept software-enabled device. This scenario also addresses both internal and external devices. Internal devices are considered first. As with all other internal originating requests, the gate keeper software implemented as an appliance or running within the firewall evaluates the request from the internal device. It will recognize that the requesting device is not a known intercept software-enabled device; by applying an exception policy to the request, gate keeper software will determine if the request is allowed. If allowed, gate keeper software will inform the receiving device that it has been cleared and is allowed to respond. If the request fails the exception policy, gate keeper will drop the request thus terminating the request. This approach prevents non-allowed connections from reaching the protected host. If the requesting device is entering from outside the network (off net), the gate keeper software also processes the exception policy in the same manner. However, this scenario also can include an internal device that has been inserted into the enterprise inappropriately, bypassing the gate keeper software or firewall. In this case, the originating device will reach the destination device (server) with a request. However, the intercept software-enabled server either terminates the request or responds back to the originating device with an inappropriate response. The connection will be terminated by the IP protocol in its normal handling of broken connections.

[0036] Scenario 4 describes non-intercept software-enabled devices connecting with other non-intercept software-enabled devices. By requiring all protected internal enterprise devices to be intercept software-enabled, no unknown devices will pass the intercept software inspection within the gate keeper protecting a trusted virtual network. Corporations that have the requirement for “outside” or global availability such as the world wide web (HTTP) and Simple Mail Transfer Protocol (SMTP) servers to be used within their buildings can provide a dedicated domain or virtual local area network (VLAN) that only has outside communication abilities.

System Architecture

[0037] The system architecture of the intercept solution of the present invention includes the following components: portal, key master software, gate keeper software and an intercept management console. FIG. 1 illustrates the system architecture of the present invention pictorially. The figure depicts users 10, 12, 14, 16, 18 connected via switch 20 and router 30 to the enterprise network 40. The enterprise network 40 can be a wide area network using the Transmission Control Protocol/Internet Protocol (TCP/IP) for network communications between devices and users. Inside the enterprise network 40 are router 60, firewall server or gate keeper appliance 70, switch 80, servers 90, 92 and mainframe 94. The intercept portal 50 and intercept management console 54 are also shown and are further described below. The master relational database management system (RDBMS) and policy manager software are installed on intercept portal 50. Key master software is installed on protected server 90 and mainframe 94, as well as on end user workstations 10, 12, 14, 16 and 18. The gate keeper software can be implemented as an appliance protecting a selected trusted virtual network (TVN) within the enterprise network.

[0038] The intercept portal 50 is a central point of initial key generation and registration. Users 10, 12, 14, 16 and 18 authenticate to the portal 50 and receive a unique software package (i.e., key master software) for their respective node. During the turn-up process users 10, 12, 14, 16 and 18 authenticate with the portal 50 using the single login used for network access as configured by the network administrator. The portal 50 verifies this authentication with the primary domain controller (PDC) and either continues with the “key master” build or terminates the attempt. The PDC is a server in a Windows NT network that maintains a read-write directory of user accounts and security information. The PDC authenticates usernames and passwords when members log into the network. Once the key master has been built, the portal 50 transfers and informs the management console 54 of the addition. The intercept administrator will then use the objective interface to drag and drop additional permission sets to the user's profile. Once the users' profiles are updated, the users 10, 12, 14, 16 and 18 are ready to access all approved resources.

[0039] Key master and gate keeper are software modules that could be simply added to existing firewalls 70 and end nodes, such as 10, 12, 14, 16 and 18. Within the firewall or appliance 70, gate keeper software provides individual session layer protection from unwanted access by controlling the initial request for connection. Node key master software provides a unique identifier for each user 10, 12, 14, 16, 18 and device; thus allowing gate keeper full recognition of who is requesting service and what service is being requested.

[0040] The intercept software (key master and gate keeper) prevents the ability to misuse resources by preventing unwanted users and non-allowed requests to make connections. Rather than terminating an existing flow, the intercept software prevents the connection all together. During times where unwanted connections are continuously being requested, intercept software will re-direct the requests to an aggregation area where security personnel can “back-through” the connection and locate the intruder. The intruder will not know that he is being tracked; thus avoidance measures will not be taken by the intruder.

[0041] Transformation/Reformation Processes

[0042] Two of the critical elements of the intercept framework are the processes of transformation and reformation. Transformation is the process of uniquely changing the values and alignment of hidden user identifiers (UID) and system identifiers (SID) that describe who the user is, what the user is attempting to use, the system being used and the active session of the on-going connection. Reformation is the process of reversing the transformed identifiers yielding the true value of each identifier. These “real” identifiers are then used to enforce access and usability policies. The objective of transformation is to provide a mechanism that prevents the transmission of usable identifiers across an open network. By transforming identifiers used by the intercept software and the TCP/IP stack before they are transmitted, potential intruders can only see what is on the wire, not what is actually being processed.

[0043] Transformation is accomplished by applying keys in a specific way that changes the original values of each identifier. These changes affect the original value and the ordering of the bits. Transformation keys are randomly selected from two key tables each containing 256 unique keys. The tables are referred to as the general key index (GKI) and the session key index (SKI), respectively. Each key has an associated key index number that points to its value. Key indexes are randomly selected by the key master software each time there is a new connection request.

[0044] The GKI table holds 256 keys that are used to change the value of an identifier. As an example, consider a UID that has a “real” value of 1234567890, a GKI key index number is randomly selected (157) and an associated key that is extracted from the GKI table. Once transformed using this key, the UID identifier's value is now changed (i.e., transformed) to 5672348901. The GKI index number is then appended to the transformed UID yielding 5672348901157.

[0045] A key index is then selected from the SKI table (e.g., 78). The SKI table holds 256 keys that are used to re-order the bits of each identifier throughout the life of the connection. Taking the above resulting number 5672348901157, the SKI key is applied transforming the number to 2319057547186. This resulting number is then used as the transmitted initial sequence number (ISN) within the TCP/IP synchronization (SYN) packet header.

[0046] As mentioned above, the intercept key master software also identifies the system being used (SID). Continuing with the above example, a computed SID is 6789012345. The SKI index number used to re-order the transformed UID number is appended yielding 678901234578. This number is then re-ordered using a third key resulting in the final acknowledgement (ACK) number 307281584697 that is included in the SYN packet header.

[0047] When the gate keeper appliance (software) intercepts the SYN packet and parses its header information, the SYN and ACK numbers are extracted. Using the third key, the software reforms the ACK number yielding the SID and SKI. The SKI is extracted and used to reform the ISN yielding a transformed UID and GKI. The GKI is used to reform the UID yielding the real UID.

[0048] Once the SYN packet has been received at its destination, the TCP/IP stack program begins parsing and processing the SYN packet normally. However, before it begins the process of verifying TCP header data, it uses the third key to reform the ACK number yielding the SID and SKI. It stores the SKI and uses it to transform/reform all incoming and outgoing packets for the duration of the connection.

[0049] Key Tables

[0050] As described above, there are two distinct key tables or arrays (GKI, SKI). Each table contains 256 128-bit keys and indexes (pointers) to each. These tables are managed and updated in one of two ways. Initially, both tables are pre-populated with all 256 keys prior to implementation in a communications network. Subsequently, the keys held in these tables can be re-populated automatically with new key values that are generated by a key generator. This automatic table feature can be scheduled based on the network owner's requirement and performed by the network's intercept software administrator.

[0051] As part of the intercept software interface and management console program, a selectable feature (“Key Table Maintenance”) option can be used by the administrator. This option schedules the tables for updating and performs replication services needed to update gate keeper appliances and key master-enabled users.

[0052] The intercept system exploits the normal operational aspects of communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP) and others. Brief descriptions of connection oriented and connectionless transport protocols are described in the following sections.

[0053] Connection Oriented Protocols

[0054] Connection oriented protocols such as TCP/IP, Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) and others rely on handshaking events to establish a connection. Connection establishment between TCP hosts is performed by using a three-way handshake mechanism. A three-way handshake synchronizes both ends of a connection by allowing both sides to agree upon initial sequence numbers. This mechanism guarantees that both sides are ready to transmit data and know that the other side is ready to transmit as well. This is necessary so that packets are not transmitted or re-transmitted during session establishment or after session termination. Each host randomly chooses a sequence number used to track bytes within a stream it is sending and receiving. The first host (host A) initiates a connection by sending a packet with the initial sequence number (ISN) and SYN bit set to indicate a connection request. The second host (host B) receives the SYN, records the sequence number, and replies by acknowledging the SYN (within ACK=ISN_(A)+1). The second host includes its own initial sequence number (ISN_(B)). An ACK=20 means that the host has received bytes 0-19 and expects byte 20 next. This technique is called forward acknowledgement. The first host then acknowledges all bytes the second host has sent with a forwarded acknowledgement indicating that the next byte the first host expects to receive is ACK=ISN_(B)+1. Data transfer can then begin. By investigating information about the requesting user, the intercept system can ensure that each requestor is calling for an allowable connection before the connection is completed. Additionally, the intercept system can identify the intent of the requestor and ensure that he is asking for a “normal” or “acceptable” service.

[0055] The fields and overall format of a TCP packet are shown in FIG. 2A. The source port and destination port fields identify points at which upper layer source and destination processes receive TCP services. The sequence number field usually specifies the number assigned to the first byte of data in the current message. In the connection-establishment phase, this field is also used to identify an initial sequence number to be used in an upcoming transmission. The acknowledgement number field contains the sequence number of the next byte of data that the sender of the packet expects to receive. The data offset field indicates the number of 32-bit words in the TCP header. The flags field carries a variety of control information, including the SYN and ACK bits used for connection establishment, and the FIN bit used for connection termination. The window field specifies the size of the sender's receive window. This represents the buffer space available for incoming data. The checksum field indicates whether the header was damaged in transit.

[0056] Connectionless Protocols

[0057] UDP, multicast and other protocols do not utilize a handshake method of establishing a connection. UDP is a connectionless transport-layer protocol that belongs to the Internet Protocol family. UDP is basically an interface between IP and upper layer processes. UDP protocol ports distinguish multiple applications running on a single device from one another. UDP is useful in situations where the reliability mechanisms of TCP are not necessary, such as in cases were a higher-layer protocol might provide error and flow control. UDP is the transport protocol for several well-known application layer protocols, including Network File System (NFS), Simple Network Management Protocol (SNMP), and Domain Name System (DNS). The UDP packet format contains four fields as shown in FIG. 2B. These include source and destination ports, length, and checksum fields. Broadcast type flows operate in a uni-directional fashion; thus the intercept system locates unique identifiers differently than those using a connection-oriented protocol but will still prevent unwanted flows by pooling the broadcast stream and verifying the initial packet of the stream.

[0058] There are two levels of device authentication and identification providing hardware and user session security. First, information about the specific device is maintained in the key master software. This information maintains a description of the hardware and is verified each time the device is used. By placing this information within the key master software, the software itself cannot be copied and placed on other devices. Without successful authentication, no network connectivity will be permitted. Secondly, unique identifiers are created each time the device is used by a user. This information is uniquely transformed and becomes part of the normal packet structure. All unique identifiers and other unique data points are computed together forming the initial sequence number (ISN) of the request. Communicating hosts exchange ISNs during connection initialization. Each host sets two counters: sequence and acknowledgement. Held within the ISN are unique keys that identify the user and are used to grant authorization. By utilizing normal protocol operands to carry authenticated identifiers, no modification to the packet structure is required; thus, intruders will notice no differences between a non-intercept software-enabled packet and an intercept software-enabled packet. Only by having a complete knowledge of how the intercept software operates, the identification of all data points used in the ISN computation and exact formulas used could a probable breach be successful.

[0059] This initial packet along with the unique identifiers are routed to its destination as usual; however on its way to the destination the packet is picked up by the gate keeper enabled appliance or firewall. The gate keeper software intercepts synchronize (SYN) packets specifically and performs reverse algorithms to the ISN, correlates encrypted identifiers to fully qualified user name (FQUN). Application and destination identifiers are also identified. It then applies availability rules to them and either forwards the SYN to its destination or rejects and drops the request. The SYN flag is only set when establishing a TCP connection.

[0060] The two major components of the intercept system software are the intercept software-enabled firewall or appliance (gate keeper) and the intercept software-enabled node (key master).

[0061] The key master module is a software component that can be added to user workstations 10, 12, 14, 16, 18 and network resources such as server 90, mainframe 94 with reference to FIG. 1. The gate keeper module is a software component that can be added to existing firewall devices or operate as a stand-alone appliance 70 as depicted in FIG. 1. As a software solution, investments and positioning of existing firewalls can be leveraged.

[0062]FIG. 3 illustrates a high level view of the major functions of the key master and gate keeper intercept software. Process blocks 200 and 210 indicate functions performed by the key master software at the originating node of a network connection. Process blocks 220, 230 and 240 indicate functions performed by the gate keeper software on intercepted packets intended for a network destination. Process blocks 250, 260 and 270 represent functions of the key master software performed at the receiving end (destination node) of a network connection. As indicated in process block 200, the originating station (source node) requests network services. Key master software is loaded and running in all enabled nodes, work stations, servers and intermediate devices. The key master software is responsible for the first level of authorization and construction of intercept-enabled packets. Leveraging the mechanics of the protocol, the key master software provides a method of identification and verification of both the hardware and the user. This is indicated in process block 210, which represents the functions of authenticating the system identification (SID), constructing and sending a SYN packet, using a session GKI/SKI.

[0063] The gate keeper in one embodiment is an in-line appliance that intercepts all packet flows associated with a protected trusted virtual network (TVN). Each packet that is routed in or out of a TVN is inspected in real time. Only the initial SYN packet is processed; all others are released without further delay. In process block 230, the GKI/SKI is extracted; the ACK and ISN are authenticated; and policy authorization is checked. SYN packets are investigated to ensure that known hardware and known users are requesting services from systems and applications that they are allowed to use. Using information held in the intercept SYN packet, profiles are compared to the requests. By looking up these individual profiles, decisions can be made to allow or disallow the connection request. The packet is released or dropped as indicated in process block 240.

[0064] At the receiving end of a connection, the receiving node accepts the SYN packet to begin the intercept-receive process. This is indicated in process block 250 with the SYN reaching its destination node. After identification of a packet type (SYN), the ACK field is evaluated and a decision is made to further process the packet. As indicated in process block 260, the SKI is extracted and used to construct the SYN/ACK. Authorization and verification is performed by extracting and transforming the ISN and ACK data and passing it to upper layer stack processes. The destination node sends a SYN/ACK to the originating node in process block 270. The key master software toggles into conversation mode throughout the rest of the connection until the FIN/ACK process informs both the originating node and the destination node of the conversation termination.

[0065] Once the SYN is received by an intercept system protected host, the host responds back in its usual manner. However, the protocol operands are once again modified. This modification is directed to how the destination device acknowledges the ISN. Rather than the standard ISN+1, the intercept system utilizes an intercept-enabled transformation algorithm and modifies the sequencing of the flow. If the connection request has originated from a non-intercept system enabled device, the normal rules of protocol handshaking will terminate the connection thus preventing the intrusion.

[0066] The gate keeper software includes the following components:

[0067] Packet grabber

[0068] Protocol factory

[0069] Packet parser

[0070] Transformer

[0071] Event broker

[0072] Re-director

[0073] Date store

[0074] Message broker

[0075] The packet grabber is responsible for selecting only the SYN packets of any given connection request. The packet grabber identifies SYN packets and send them to the protocol factory for further processing. Only SYN packets are grabbed.

[0076] The protocol factory is responsible for identifying the protocol and calling the proper parser for packet parsing functions.

[0077] The packet parser selects specific header and frame information about the SYN packet. It then performs look up functions to verify permissions and key identification by calling the transformer. The packet parser makes the decision to allow the connection, terminate the connection request or re-direct the request to the intercept system console. It uses the data store as a decision support tool.

[0078] The transformer reverse computes the transformed identifiers which contains unique key data. This key data identifies the user making the request. Rules are applied to this data so the packet parser can make a go/no-go decision.

[0079] The event broker executes the actions as directed by the packet parser, either allowing the connection, dropping the connection request or requesting re-direction. The event broker also logs requests and their actions.

[0080] The re-director takes data from the event broker and directs it to multiple places as defined. The data store is used to maintain key identifiers and permissions. It is automatically updated through the message broker.

[0081] The message broker provides synchronized replication of changed data so every known intercept software-enabled appliance or firewall has current up-to-date policy data.

[0082] Key master software is device driver software only. It modifies the methodology controlling the creation and interpretation of unique SYN sequence numbers and acknowledgement (ACK) numbers. Using both the digital key and fixed formulas, it generates a unique 32-bit sequence number and ACK number. Held within the sequence number are identifiers for the active session and user ID. Held within the acknowledgement number are identifiers for the hardware and transformation keys. Although intercept software creates unique numbers they adhere to all Internet Engineering Task Force (IETF) Request for Comments (RFC) standards regarding protocol use of those numbers. As such, no modifications are needed to normal infrastructure operations and packet delivery.

[0083] In order to “turn-up” a new intercept system-enabled user, the user needs to be added to the intercept system data store and have a unique key master (SID) created. The key master software utilizes the original media access control hardware (MAC) address embedded as part of the SID and determines if the requesting workstation's present MAC address is the same as the registered address. The SID is created by taking the MAC address of the user's workstation plus the actual time stamp of the addition (measured in milliseconds).

[0084] This comparison prevents unknown devices from being connected at trusted locations such as a wiring closet. Additionally, it prevents illicit copies of the key master SID from being installed on unwanted systems. If the MAC address comparison fails, key master software informs the administrator and disallows connectivity.

[0085] When the user's workstation is enabled, he can use an application resource. When the user generates a request for connection, the key master software creates a unique SYN/ISN containing a 24-bit CRC of the UID that has been transformed plus a randomly selected GKI. The UID is a fully qualified user name FQUN plus the domain name. This is computed by taking the user ID name (e.g., dshay) and the authenticated domain name and computing a 24-bit numerical value. The CRC is computed by taking the UID and computing a normal cyclic redundancy check (CRC).

[0086] These numbers are then combined and computed using a transformation algorithm to create the unique SYN/ISN. Additionally, key master software computes a unique SID by taking the MAC address of the active network interface card and the stored time stamp and creating a 24-bit CRC numerical value. A randomly selected SKI is then combined to this 24-bit number and the resulting 32-bit number is transformed to create the ACK number. Because the uniquely generated sequence number and ACK numbers are 32 bits in length, they don't alter any requirements specified by the RFCs governing the TCP/IP protocol.

[0087] The complete SYN packet is then normally routed through the network, heading towards its destination. Before it reaches its destination address; however, the packet is picked up by the gate keeper software. It begins by evaluating the ACK number. If the ACK number contains a zero value the request is recognized as an untrusted request and is processed by the exception policy. The exception policy is applied to verify a pre-existing policy for untrusted requesting sources. If the exception request is granted gate keeper assigns a unique identifiable ACK number that is understood by enabled receiving devices; if no exception policy exists the request is dropped. If the request is not identified as an exception (a non-zero ACK number), it is processed as an enabled request. As a normal enabled SYN packet, gate keeper reforms the received ACK number yielding the SID and SKI. The SKI is then used to reform the ISN yielding a transformed UID and the GKI. The GKI is then used to reform the UID yielding a real UID. Continuing the process, gate keeper then verifies the UID and selects the level of policy to apply. If no other policy is defined for the UID, the packet is released. However, if additional levels of policy are defined, gate keeper verifies each policy component. These policy components can include authorization of the hardware device by verifying the SID, application authorization by verifying the destination port identifier or any combination including all components.

[0088] From the combination of this information, the following is known:

[0089] intercept system-enabled request packet coming from a known device;

[0090] the identification of the user that is making the request for connection; and

[0091] where the user wants to go (destination) and what the user wants to do (resources).

[0092] A set of permissions (i.e., policy) can now be evaluated for each individual user. If user “dshay” is authenticated to his normal domain, the intercept system will be able to recognize the user within the data store and allow him to work within his restrictions. If the user (dshay) needs to use someone else's workstation, he will still need to find an intercept system-enabled node. In addition, the user will still have to authenticate to his normal domain and be recognized by either the Primary Data Controller (PDC) or the intercept system. As discussed above, the PDC authenticates user names and passwords when members log into the network. Members only have to log into one domain to access all resources in the network.

[0093]FIG. 4 illustrates the processing logic implemented in the key master software to control requests from end users for network connection services. Processing starts in logic block 400 with the user performing a TCP/IP Open call requesting a connection to a network service. From an operating system perspective, end user workstations requesting a service ask the TCP services program to open a new connection request which starts the functions needed to build a request packet (SYN) and to prepare the packet for transmission.

[0094] The TCP protocol requires the establishment of a controlled connection between two devices before data can be exchanged. As defined by RFC 793, this connection process requires the requesting device to send an Initial Sequence Number (ISN) so that the connection can have a starting point shared by both devices. As noted previously, the ISN is a 32-bit integer that is randomly generated by the stack. The interceptor takes control of the method by which this number is generated and creates an ISN that holds a previously computed UID. The UID is then used to identify the individual user making the request before the request packet is received at its destination.

[0095] Before the connection request is processed, the key master software obtains the identification of the requesting machine (SID) and the user account identification (UID). By obtaining the Media Access Control (MAC) address of the network interface card (NIC) along with the original time stamp previously stored, a 24-bit transformed SID is created. This processing step is indicated by logic block 404. Located in the key master software, this function call is executed before the Open call, therefore it controls the go/no go state. By intercepting the connection request, authorization decisions can be made before an intruder has connected to the network.

[0096] In decision block 406, a determination is made as to whether the machine (i.e., workstation) requesting connection is the same machine authorized during the registration process or “turn-up.” By comparing the MAC address portion of the computed SID with the actual MAC address of the machine, the key master software can determine if the machine is the same machine used during turn-up. If the key master software has been copied to another machine, or the access request is bound to a known network interface card (NIC), the session values will not match the stored values and the request will be terminated. If the authentication check fails in decision block 406, the key master software defaults to a non-enabled operating mode preventing access to protected systems. The key master software can also notify the security administrator of the failed attempt to connect as indicated in logic block 408. This message is reported and stored in the event database within the portal RDBMS. This information can be used to identify and track unauthorized events. For example, this can be useful to network administrators in detecting and taking countermeasures against a threat posed by such unauthorized access attempt. In addition, a record of such unauthorized access attempt can be useful for investigation of cyber crimes associated with such unauthorized access attempt. Such record can also be used as forensic evidence of attempted misappropriation, trespass, or other crime, for example, to assist in prosecution thereof.

[0097] The key master software includes two arrays of transformation keys. Each array has index pointers that are associated with a key's value. Such index pointers are referred to as the GKI and the SKI. In the presently preferred embodiment, the arrays of session and general keys comprises two-hundred-fifty-six (256) different key values and corresponding indexes GKI and SKI. The indexes GKI and SKI are eight (8) bits in length, and the keys are two-hundred-fifty-six (256) bits in length. However, those of ordinary skill in the art will understand that the size of the arrays and bit lengths of the indexes GKI and SKI, and their associated keys, can be set to virtually any usable length without departing from the scope of the invention. After the UID has been computed, a GKI and an SKI are selected for the transformation steps. This processing step is indicated in logic block 410. The previously computed UID is transformed as indicated in logic block 412. More specifically, a hash algorithm such as a twenty-four (24) bit cyclic redundancy check (known as “CRC-24”) is used to generate a twenty-four (24) bit hash from the UID.

[0098] As indicated in logic block 414, the GKI is added to the resulting transformed UID. In logic block 416, the SID is transformed. More specifically, the SID is subjected to a hash algorithm such as CRC-24, and the resulting hash constitutes the transformed SID. The selected SKI is appended to the transformed hash computed from the SID, as indicated in logic block 418. The transformed UID and appended GKI are inserted into the ISN field of the SYN packet, as indicated in Step 420. The transformed SID and appended SKI are entered into the ACK field of the SYN packet in Step 422. The SYN packet is thus made ready for transmission from the source node to the destination node.

[0099] So that the source node will be able to authenticate the destination node when it acknowledges the SYN packet, the source node performs Steps 424-430. Although the result of these steps is not transmitted with the SYN packet from the source to destination node, these steps are performed by the source node to enable it to authenticate the response message from the destination node, which acknowledges the SYN packet. In Step 424, the source node creates a session identifier by concatenating the 32-bit transformed UID and appended GKI, and 32-bit SID and appended SKI, to produce a 64-bit session identifier. This session identifier is encrypted using the key value referenced by the GKI using an encryption routine, which can be the well-known DES1 algorithm, for example. In step 428, the source node performs a hash routine such as the well-known SHA1 procedure, to generate a 192-bit result. The lower 64-bits of this 192-bit result are stored for later retrieval and comparison with the same fields of a response message from the destination node. In Step 432 the source node transmits the SYN packet from the source node to the destination node to initiate communication therewith.

[0100] The processing logic associated with the authentication process performed by the gate keeper software is illustrated in FIG. 5. As shown in FIG. 1, the gate keeper 70 is an in-line active device. It performs services similar to a typical firewall. It receives all packets that flow bi-directionally on network circuits, investigates each packet, selects only specific packets for further processing, and releases all other packets. The processing logic for the gate keeper software can be delineated into a number of processing blocks that are shown in FIG. 5. These process blocks include promiscuous packet capture; protocol identification and packet identification; parsing and fetching; transformation/reformation; authorization verification; connection action; and notification. When executing in promiscuous mode, every packet transmitted on to a protected circuit is captured and placed in the input buffer. Protocol identification is performed by evaluating the IP header data in the packet. Once the protocol type code is identified as TCP, the packet header is again evaluated for an active SYN flag. If the packet is a SYN packet, it is then further processed. If it is not an SYN packet, the packet is immediately released and sent on to its destination.

[0101] Processing commences in logic block 500 with the step of receiving a packet flow from a node. In step 502, the received packet is parsed. In decision block 504, a test is made to determine if the packet is a TCP packet. If it is, then in decision block 506, a test is made to determine if the packet is an SYN packet. If it is not a SYN packet, the packet is released as indicated in step 508. Once the packet has been declared a TCP packet with the SYN flag set, the ACK field is verified. In decision block 512, if the ACK field has a value greater than zero, then the ACK value and extracted SID/SKI are reformed as indicated in logic block 516. If the ACK field has a value of zero, an exception routine is then performed as indicated in logic block 514. Further details associated with the performance exception routine are depicted in FIG. 6. Following the reform process in logic block 516, the ISN is reformed. The reformed ISN reveals the transformed UID and the GKI as indicated in logic block 518. The resulting UID is verified in logic block 524. If this is found to be a bad index number, the connection request is dropped. The resulting UID is then searched for in the data store containing all known user profiles. A test is made in decision block 526 to determine if the UID has been found. If the UID has been found, then it is passed on to the next processing block, logic block 532 for further authentication. If the resulting UID is not found (decision block 526), the connection request is dropped (logic block 528) and a message is sent to the administrator as indicated in block 530.

[0102] After the UID has been found (yes path out of decision block 526), the UID process policy is inspected in logic block 532. This inspection informs the gate keeper software of the level of policy in effect for this user. The process flags the five levels of policy to apply to each user. These policies provide for the inspection of user (U), hardware (H), requested application (A), requested destination (D), and no policy at all (N). In decision block 534, a test is made to determine if there is a hardware or a requested application policy defined for the user. If a hardware policy is defined, the SID is then verified as indicated in logic block 536. The SID identifies the source node making the request. A test is performed in decision block 538 to determine if the SID has been found. If the SID has not been found, then the request is dropped (logic block 540) and a message is sent to the administrator as indicated in block 542. If the test in decision block 538 passes, the packet is released to the destination, as indicated in logic block 546. In decision block 534, if an application policy is defined, the destination port is verified (logic block 548). In decision block 550, a test is made to determine if the user is authorized to access the requested application. If the user is so authorized, the packet is released to the destination as indicated in logic block 560. Otherwise, the request is dropped (logic block 528) and a message is sent to the administrator as indicated in logic block 530. If neither a hardware policy nor a requested application policy is defined for the user, a test is then made in decision block 544 to determine if there is either a requested destination policy or no policy at all defined for the user. If a requested destination policy is defined, a destination port is verified in logic block 552. If a destination port is accessible to the user, then the packet is released to the destination as indicated in logic block 560. If in decision block 554, the destination port is not available to the user, the request is dropped (logic block 556) and a message is sent to the administrator, as indicated in block 558.

[0103]FIG. 6 illustrates the processing logic associated with the “performing exception” process. When the value held in the ACK field is zero, the gatekeeper software knows that the packet has originated from an untrusted source. The exception routine is executed because of the requirement to provide selected untrusted source access. The origination source address is extracted from the IP layer in the verified source address logic block 600. The extracted source address is then verified from the exception table as indicated in decision block 602. If this test fails, the connection request is dropped (logic block 604) and a message is sent to the administrator in logic block 606. If the extracted source address is verified as a non-address in decision block 602, the requested destination is then verified by extracting the destination address in the IP layer. This is indicated in logic block 608. The extracted destination address is then verified from the exception table in decision block 610. If the test fails, the request is dropped in logic block 604. If the extracted destination address is verified in decision block 610, then the packet is further tested by extracting the destination port number from the TCP layer to verify the application request in logic block 612. The destination port number is then verified in the exception table as indicated in decision block 614. If the test fails, the request is dropped in logic block 604. If the test passes in decision block 614, the request is then ready for transformation. This transformation occurs in logic block 616 with the generation of a unique initial ACK number (IACK). This unique number will be authenticated by the key master software at the destination node as a recognized gate keeper-induced number. An SKI is selected next, as indicated in logic block 618. The selected SKI is then added to the IACK in logic block 620. The resulting number is then transformed in logic block 622 and stored as the ACK in logic block 624. The SYN packet is finally reassembled and the CHECKSUM is recalculated in logic block 626. The SYN packet is then released as indicated in logic block 628.

[0104]FIG. 7 illustrates the processing logic associated with call set up and response from a destination node, after receiving the packet from gate keeper appliance 70. Processing starts in decision block 700 with a test to determine if an incoming packet is an SYN packet. The incoming packet is inspected and tested for the SYN flag being set. If the SYN flag is set in the packet, set up processing is required. If the SYN flag is not set, the packet is not an SYN packet and the packet is deemed as being associated with an established connection and is processed differently (see FIG. 8). If the SYN flag is set, then a test is performed in decision block 702 to determine if the ACK field is equal to zero. This test protects against untrusted nodes establishing a connection. If the ACK field is zero, the packet is dropped in logic block 704 and a message sent to the administrator in block 706. If the ACK field is non-zero, further connection set up processing is performed. The ACK is reformed utilizing the static routine in logic block 708, and the SID is extracted from the reformed ACK number. The SID is evaluated in step 712 to determine whether it has a special value indicating that the packet is an exception and should not be processed in the normal manner. If the ACK is not an exception, normal processing proceeds in Step 714 in which the SKI is extracted from the ACK field and is stored in a buffer in Step 716. In Step 718 the ISN is reformed to restore the transformed UID and GKI, and the ISN is stored in the buffer in Step 720. Following Step 720, processing proceeds to Step 722 in which the ACK field is zeroed. Alternatively, if the determination of Step 712 establishes that the ACK field indicates that the packet is an exception, in Step 724 the destination node turns off all transformation processes in Step 724 and proceeds to Step 722 in which the ACK field of the SYN packet is zeroed. In step 726, the ACK is stored in memory. In Step 728 normal TCP/IP stack processing of the packet is executed by the destination node, resulting in generation of an acknowledgement message destined for the source node initiating communication. In Step 730 the destination node applies session transformation routines to the outgoing packets. Step 730 of FIG. 7 involves the same processing as Steps 424-430 of FIG. 4, resulting in generation of new ISN and ACK values for corresponding fields of the response packet. These new values effectively prevent hi-jacking of the connection as it is being set up, which is a common technique of hackers. In Step 732, the destination node transmits the response packet to the source node by executing the tcp_send ( ) function.

[0105]FIG. 8 illustrates the non-SYN packet processing flow that is executed after a connection has been established. In Step 800 a node receiving a packet determines whether the packet is related to an established connection. The node can determine this fact by comparing the values of the ISN and ACK fields with corresponding values previously stored for the session at the node. If the values match, then the packet communication is related to an existing connection. Conversely, if the values do not match, then the packet does not relate to any existing connection, and the packet is dropped in Step 802. If the packet does relate to an existing connection, in Step 804 the packet is reformed using the session transformations. In Step 806 the sequence number is extracted from the packet and stored, and the acknowledgement number is extracted from the packet and stored in Step 808. In Step 810, the node executes normal TCP/IP stack processing of the packet. In Step 812 the node transforms the sequence number and ACK numbers resulting from normal stack processing using the session keys indicated by the GKI and SKI. The response packets are put in the transmit buffer by the stack, and the response packets with transformed sequence and ACK values are transmitted to the opposite node in Step 814.

[0106] The present invention can be realized in hardware, software, or a combination of hardware and software. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. The techniques of the present invention can also be embedded in a computer program product, which comprises part or all of the features enabling the implementation of the methods described herein, and which, when loaded in a computer system, is able to carry out these methods.

[0107] Computer program in the present context mean any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following occur: a) conversion to another language, code or notation; b) reproduction in a different material form. Computer program also encompasses hard-wired instructions embedded in an electronic device including semiconductor chips or cards, network appliances, routers, switches, servers, firewalls and client devices such as network computers, workstations, desktop computers, laptop computers and handheld devices. Specifically, a number of functions performed at the protocol or packet level can be embedded in Application Specific Integrated Circuits (ASICs). Such functions can include the parsing or routing of packets. The invention can also be embedded in single board computers (SBCs) with a Linux operating system and silicon-based data storage. Multiple boards can be installed in slots in a chassis as “blades” (similar to router blades in a router chassis) thus providing multiple gate keeper appliances.

[0108] It should be understood that the present invention has application beyond the network security context. For example, the fact that a user and/or source identifier can be included in a packet header permits routing and switching of packet communication by a receiving node based on user and/or source identified in the packet header. Such routing and/or switching can be in addition to or in lieu of routing by destination, which is typical in packet communications. Thus, it should be understood that the capability of including the user and/or source identifier in a packet header greatly expands the application and uses of the disclosed invention.

[0109] The corresponding structures, materials, acts, and equivalents of any mean plus function elements in any claims are intended to include any structure, material or acts for performing the function in combination with the other claimed elements as specifically claimed.

[0110] While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various other changes in form and detail may be made without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A method comprising: including data based on at least one of a user identifier and a source identifier in a header of a packet.
 2. A method as claimed in claim 1 wherein the data identifying the user identifier is included in a sequence number field of the packet.
 3. A method as claimed in claim 1 wherein the data identifying the source identifier is included in an acknowledgement field of the packet.
 4. A method as claimed in claim 3 wherein the data in the acknowledgement field has a non-zero value.
 5. A method as claimed in claim 1 further comprising: transforming at least one of the user identifier and source identifier to generate the data for inclusion in the header of the packet.
 6. A method as claimed in claim 5 wherein the transforming is performed using a cyclic redundancy check (CRC) algorithm.
 7. A method as claimed in claim 5 wherein the data indicating the transformed user identifier is included in a sequence number field of the packet.
 8. A method as claimed in claim 7 further comprising: appending a first key index to the transformed user identifier to generate the data for inclusion in the sequence number field of the packet.
 9. A method as claimed in claim 8 wherein the data indicating the transformed source identifier is included in the acknowledgement field of the packet.
 10. A method as claimed in claim 9 further comprising: appending a second key index to the transformed source identifier to form the data for inclusion in the acknowledgement field of the packet.
 11. A method as claimed in claim 10 wherein the data included in the acknowledgement field has a non-zero value.
 12. A method as claimed in claim 5 further comprising: appending a key index to the transformed source identifier to generate the data for inclusion in the acknowledgement field of the packet.
 13. A method as claimed in claim 1 wherein at least one of the user identifier and source identifier has a non-zero value that is included in the acknowledgement field of the header of the packet.
 14. A method as claimed in claim 1 wherein the user identifier indicates a user associated with a source node that initiates communication over a network with a destination node by transmitting the packet from the source node to the destination node.
 15. A method as claimed in claim 14 wherein the user identifier comprises a user name of the user.
 16. A method as claimed in claim 1 wherein the source identifier indicates a source node that initiates communication over a network with a destination node by transmitting the packet from the source node to the destination node.
 17. A method as claimed in claim 16 wherein the source identifier is based on a media access control (MAC) address of the source node.
 18. A method as claimed in claim 17 wherein the source node comprises a desktop computer, a laptop computer, personal digital assistant (PDA), or other computing device.
 19. A method as claimed in claim 1 wherein the packet has a transfer control protocol/Internet protocol (TCP/IP) format.
 20. A method as claimed in claim 1 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 21. A method comprising: transforming a user identifier; appending a first key index to the user identifier; and including the transformed user identifier and appended first key index in a first field of a header of a packet.
 22. A method as claimed in claim 21 wherein the user identifier comprises a user name of a user of a node initiating communication with another node using the packet.
 23. A method as claimed in claim 21 wherein the user name is subjected to a cyclic redundancy check (CRC) algorithm to generate the transformed user identifier.
 24. A method as claimed in claim 21 wherein the node comprises a desktop computer, laptop computer, personal digital assistant (PDA), or other computing device.
 25. A method as claimed in claim 21 wherein the packet is a synchronization (SYN) packet.
 26. A method as claimed in claim 21 wherein the first field comprises a sequence number field.
 27. A method as claimed in claim 21 further comprising: transforming a source identifier; appending a second key index to the source identifier; and including the transformed source identifier and appended second key index in a second field of the packet header.
 28. A method as claimed in claim 27 wherein the source identifier identifies a node initiating communication with another node using the packet.
 29. A method as claimed in claim 27 wherein the source identifier is a media access control (MAC) address.
 30. A method as claimed in claim 29 wherein the node comprises at least one of a desktop computer, laptop computer, personal digital assistant (PDA), or other computing device.
 31. A method as claimed in claim 27 wherein the source identifier is subjected to a cyclic redundancy check (CRC) algorithm to generate the transformed source identifier.
 32. A method as claimed in claim 27 wherein the packet is a synchronization (SYN) packet.
 33. A method as claimed in claim 27 wherein the second field comprises an acknowledgement field.
 34. A method as claimed in claim 27 further comprising: creating a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypting the session identifier using a first key identified by the first key index; generating a hash based on the encrypted session identifier; and storing at least part of the hash.
 35. A method as claimed in claim 34 further comprising: transmitting the packet including the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 36. A method as claimed in claim 35 further comprising: receiving an acknowledgement packet from the destination node in response to the transmitted packet.
 37. A method as claimed in claim 36 further comprising: extracting data from at least one field of the packet; comparing data from the packet with the hash; dropping the packet if the extracted data and hash fail to match; and continuing processing of the packet if the extracted data and the hash match.
 38. A method as claimed in claim 37 further comprising: transmitting the packet including the data indicating the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 39. A method as claimed in claim 38 further comprising: receiving an acknowledgement packet from the destination node in response to the transmitted packet.
 40. A method as claimed in claim 27 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 41. A method comprising: generating a packet with a header having a transformed user identifier, a first key index, a transformed session identifier, and a second key index; creating a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypting the session identifier using the first key identified by the first key index; and generating a hash based on the session identifier; and storing at least part of the hash.
 42. A method as claimed in claim 41 further comprising: transmitting the packet including the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 43. A method as claimed in claim 42 further comprising: receiving an acknowledgement packet from the destination node in response to the transmitted packet.
 44. A method as claimed in claim 43 further comprising: extracting data from the packet; comparing data from the packet with the hash; dropping the packet if the extracted data and hash fail to match; and continuing processing of the packet if the extracted data and the hash match.
 45. A method as claimed in claim 41 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 46. A method comprising: extracting data based on at least one of a user identifier and a source identifier from a header of a packet.
 47. A method as claimed in claim 46 wherein the data is extracted from a header of the packet.
 48. A method as claimed in claim 46 wherein the packet is a synchronization (SYN) packet.
 49. A method as claimed in claim 46 wherein the user identifier is derived from a user name of a user originating the packet.
 50. A method as claimed in claim 46 wherein the source identifier is derived from a media access control (MAC) address associated with a node originating the packet.
 51. A method as claimed in claim 46 wherein the data includes a transformed user identifier.
 52. A method as claimed in claim 51 wherein the transformed user identifier is generated with a cyclic redundancy check (CRC) algorithm.
 53. A method as claimed in claim 46 wherein the data includes a transformed source identifier.
 54. A method as claimed in claim 53 wherein the transformed source identifier is generated with a cyclic redundancy check (CRC).
 55. A method as claimed in claim 46 wherein the data extracted from the packet further comprises at least one key index identifying a key.
 56. A method comprising: receiving a packet having a transformed user identifier, first key index, transformed source identifier, and second key index; extracting a transformed user identifier, first key index, transformed source identifier, and second key index from a packet; creating a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypting the session identifier using the first key identified by the first key index; and generating a hash based on the session identifier.
 57. A method as claimed in claim 56 wherein the packet is a synchronization (SYN) packet originating from a first node and received at a second node, the method further comprising: including at least part of the hash for inclusion in a response packet for transmission from the second node to the first node.
 58. A method as claimed in claim 57 wherein the part of the hash comprises the lower sixty-four (64) bits of the hash.
 59. A method as claimed in claim 56 wherein the user identifier is transformed using a cyclic redundancy check (CRC) algorithm.
 60. A method as claimed in claim 56 wherein the encrypting is performed using a DES algorithm.
 61. A method as claimed in claim 56 wherein the hash is generated using a SHA-1 algorithm.
 62. A method comprising: receiving a packet; extracting a user identifier and source identifier from the packet; checking authorization policy based on the user identifier and source identifier to determine whether the user and source are authorized to pass to a destination indicated by the packet; releasing the packet if the checking indicates that the packet is permitted by the policy to pass to its destination; and dropping the packet if the authorization policy indicates that the packet is not permitted to pass to its destination.
 63. A method as claimed in claim 62 wherein the packet is a synchronization (SYN) packet.
 64. A method as claimed in claim 62 wherein the user identifier is based on a user name of a user of a node originating the packet.
 65. A method as claimed in claim 62 wherein the source identifier is based on a media access control (MAC) address of a node originating the packet.
 66. A method as claimed in claim 62 wherein the source identifier authorization policy is further defined based on a resource indicated by a destination of the packet.
 67. A method as claimed in claim 66 wherein the resource is an application.
 68. A method as claimed in claim 66 further comprising: creating a record of the failed access attempt if the packet is dropped.
 69. A method as claimed in claim 66 further comprising: notifying an administrator of the failed access attempt if the packet is dropped.
 70. A method as claimed in claim 66 further comprising: creating a session identifier based on the transformed user identifier, the first key index, the transformed source identifier, and the second key index; encrypting the session identifier using the first key identified by the first key index; generating a hash based on the session identifier; including the hash in a response packet for transmission to the node originating the received packet; and transmitting the response packet to the node originating the received packet.
 71. A system comprising: a first node generating a packet including data based on a user identifier and source identifier; a second node receiving the packet and determining whether the packet is to be released to its destination based on an authorization policy defined for the user identifier and source identifier of the packet; and a third node receiving and processing the packet if the second node releases the packet to the third node.
 72. A system as claimed in claim 71 wherein the packet is a synchronization (SYN) packet defined in transfer control protocol/Internet protocol (TCP/IP) format.
 73. A system as claimed in claim 71 wherein at least one of the first, second, and third nodes comprises a desktop computer, laptop computer, personal digital assistant, or other computing device.
 74. A system as claimed in claim 71 wherein the first and second nodes are connected via the Internet.
 75. A system as claimed in claim 71 wherein the second and third nodes are connected via an intranet.
 76. A system as claimed in claim 71 wherein the user identifier is based on a user name of a user of a node originating the packet.
 77. A system as claimed in claim 71 wherein the source identifier is based on a media access control (MAC) address of a node originating the packet.
 78. A system as claimed in claim 71 wherein the authorization policy is further defined based on a resource indicated by a destination of the packet.
 79. A system as claimed in claim 71 wherein the resource is an application.
 80. A system as claimed in claim 71 wherein the authorization policy is further defined based on a destination of the packet.
 81. A system as claimed in claim 71 further comprising: creating a record of the failed access attempt if the packet is dropped.
 82. A system as claimed in claim 71 further comprising: notifying an administrator of the failed access attempt if the packet is dropped.
 83. An apparatus comprising: a node for including data based on at least one of a user identifier and a source identifier in a header of a packet.
 84. An apparatus as claimed in claim 83 wherein the data identifying the user identifier is included in a sequence number field of the packet.
 85. An apparatus as claimed in claim 83 wherein the data identifying the source identifier is included in an acknowledgement field of the packet.
 86. An apparatus as claimed in claim 83 wherein the data in the acknowledgement field has a non-zero value.
 87. An apparatus as claimed in claim 83 wherein the node transforms at least one of the user identifier and source identifier to generate the data for inclusion in the header of the packet.
 88. An apparatus as claimed in claim 87 wherein the node transforms at least one of the user identifier and source identifier using a cyclic redundancy check (CRC) algorithm.
 89. An apparatus as claimed in claim 87 wherein the data indicating the transformed user identifier is included in a sequence number field of the packet.
 90. An apparatus as claimed in claim 89 wherein the node appends a first key index to the transformed user identifier to generate the data for inclusion in the sequence number field of the packet.
 91. An apparatus as claimed in claim 90 wherein the data indicating the transformed source identifier is included in the acknowledgement field of the packet.
 92. An apparatus as claimed in claim 91 wherein the node appends a second key index to the transformed source identifier to form the data for inclusion in the acknowledgement field of the packet.
 93. An apparatus as claimed in claim 92 wherein the data included in the acknowledgement field has a non-zero value.
 94. An apparatus as claimed in claim 87 wherein the node appends a key index to the transformed source identifier to generate the data for inclusion in the acknowledgement field of the packet.
 95. An apparatus as claimed in claim 83 wherein at least one of the user identifier and source identifier has a non-zero value that is included in the acknowledgement field of the header of the packet.
 96. An apparatus as claimed in claim 83 wherein the user identifier indicates a user associated with a source node that initiates communication over a network with a destination node by transmitting the packet from the source node to the destination node.
 97. An apparatus as claimed in claim 96 wherein the user identifier comprises a user name of the user.
 98. An apparatus as claimed in claim 83 wherein the node identified by the source identifier is a source node that initiates communication over a network with a destination node by transmitting the packet from the source node to the destination node.
 99. An apparatus as claimed in claim 98 wherein the source identifier is based on a media access control (MAC) address of the source node.
 100. An apparatus as claimed in claim 98 wherein the source node comprises a desktop computer, a laptop computer, personal digital assistant (PDA), or other computing device.
 101. An apparatus as claimed in claim 83 wherein the packet has a transfer control protocol/Internet protocol (TCP/IP) format.
 102. An apparatus as claimed in claim 83 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 103. An apparatus comprising: a node for transforming a user identifier, appending a first key index to the user identifier, and including the transformed user identifier and appended first key index in a first field of a header of a packet.
 104. An apparatus as claimed in claim 103 wherein the user identifier comprises a user name of a user of a node initiating communication with another node using the packet.
 105. An apparatus as claimed in claim 103 wherein the user name is subjected to a cyclic redundancy check (CRC) algorithm to generate the transformed user identifier.
 106. An apparatus as claimed in claim 103 wherein the node comprises a desktop computer, laptop computer, personal digital assistant (PDA), or other computing device.
 107. An apparatus as claimed in claim 103 wherein the packet is a synchronization (SYN) packet.
 108. An apparatus as claimed in claim 103 wherein the first field comprises a sequence number field.
 109. An apparatus as claimed in claim 103 wherein the node further transforms a source identifier, appends a second key index to the source identifier, and includes the transformed source identifier and appended second key index in a second field of the packet header.
 110. An apparatus as claimed in claim 109 wherein the source identifier identifies a node initiating communication with another node using the packet.
 111. An apparatus as claimed in claim 109 wherein the source identifier is a media access control (MAC) address.
 112. An apparatus as claimed in claim 109 wherein the node comprises at least one of a desktop computer, laptop computer, personal digital assistant (PDA), or other computing device.
 113. An apparatus as claimed in claim 109 wherein the source identifier is subjected to a cyclic redundancy check (CRC) algorithm to generate the transformed source identifier.
 114. An apparatus as claimed in claim 109 wherein the packet is a synchronization (SYN) packet.
 115. An apparatus as claimed in claim 109 wherein the second field comprises an acknowledgement field.
 116. An apparatus as claimed in claim 109 further comprising: creating a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypting the session identifier using a first key identified by the first key index; generating a hash based on the encrypted session identifier; and storing at least part of the hash.
 117. A method as claimed in claim 116 further comprising: transmitting the packet including the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 118. A method as claimed in claim 117 further comprising: receiving an acknowledgement packet from the destination node in response to the transmitted packet.
 119. A method as claimed in claim 116 further comprising: extracting data from at least one field of the acknowledgement packet; comparing data from the acknowledgement packet with the hash; dropping the acknowledgement packet if the extracted data and hash fail to match; and continuing processing of the acknowledgement packet if the extracted data and the hash match.
 120. A method as claimed in claim 83 further comprising: transmitting the packet including the data indicating the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 121. A method as claimed in claim 120 further comprising: receiving an acknowledgement packet from the destination node in response to the transmitted packet.
 122. A method as claimed in claim 83 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 123. An apparatus comprising: a node for generating a packet with a header having a transformed user identifier, a first key index, a transformed session identifier, and a second key index; creating a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypting the session identifier using the first key identified by the first key index; generating a hash based on the session identifier; and storing at least part of the hash.
 124. An apparatus as claimed in claim 123 wherein the node further transmits the packet including the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 125. An apparatus as claimed in claim 124 wherein the node further receives an acknowledgement packet from the destination node in response to the transmitted packet.
 126. A method as claimed in claim 123 wherein the node further extracts data from the packet, compares data from the packet with the hash, drops the packet if the extracted data and hash fail to match, and continues processing of the packet if the extracted data and the hash match.
 127. A method as claimed in claim 123 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 128. An apparatus comprising: a node for extracting data based on at least one of a user identifier and a source identifier from a header of a packet.
 129. An apparatus as claimed in claim 128 wherein the data is extracted from a header of the packet.
 130. An apparatus as claimed in claim 128 wherein the packet is a synchronization (SYN) packet.
 131. An apparatus as claimed in claim 128 wherein the user identifier is derived from a user name of a user originating the packet.
 132. An apparatus as claimed in claim 128 wherein the source identifier is derived from a media access control (MAC) address associated with a node originating the packet.
 133. An apparatus as claimed in claim 128 wherein the data includes a transformed user identifier.
 134. An apparatus as claimed in claim 133 wherein the transformed user identifier is generated with a cyclic redundancy check (CRC) algorithm.
 135. An apparatus as claimed in claim 128 wherein the data includes a transformed source identifier.
 136. An apparatus as claimed in claim 135 wherein the transformed source identifier is generated with a cyclic redundancy check (CRC) algorithm.
 137. An apparatus as claimed in claim 128 wherein the data extracted from the packet further comprises at least one key index identifying a key.
 138. An apparatus comprising: a node for receiving a packet having a transformed user identifier, first key index, transformed source identifier, and second key index; extracting a transformed user identifier, first key index, transformed source identifier, and second key index from a packet; creating a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypting the session identifier using the first key identified by the first key index; and generating a hash based on the session identifier.
 139. An apparatus as claimed in claim 138 wherein the packet is a synchronization (SYN) packet originating from a first node and received at a second node, the node further including at least part of the hash for inclusion in a response packet for transmission from the second node to the first node.
 140. An apparatus as claimed in claim 138 wherein the part of the hash comprises the lower sixty-four (64) bits of the hash.
 141. A method as claimed in claim 138 wherein the user identifier is transformed using a cyclic redundancy check (CRC) algorithm.
 142. A method as claimed in claim 138 wherein the encrypting is performed using a DES algorithm.
 143. A method as claimed in claim 138 wherein the hash is generated using a SHA-1 algorithm.
 144. An apparatus comprising: a node for receiving a packet; extracting a user identifier and source identifier from the packet; checking authorization policy based on the user identifier and source identifier to determine whether the user and source are authorized to pass to a destination indicated by the packet; releasing the packet if the checking indicates that the packet is permitted by the policy to pass to its destination; and dropping the packet if the authorization policy indicates that the packet is not permitted to pass to its destination.
 145. A node as claimed in claim 144 wherein the packet is a synchronization (SYN) packet.
 146. A node as claimed in claim 144 wherein the user identifier is based on a user name of a user of a node originating the packet.
 147. A node as claimed in claim 144 wherein the source identifier is based on a media access control (MAC) address of a node originating the packet.
 148. A node as claimed in claim 144 wherein the source identifier authorization policy is further defined based on a resource indicated by a destination of the packet.
 149. A node as claimed in claim 144 wherein the resource is an application.
 150. A node as claimed in claim 144 wherein the node creates a record of the failed access attempt if the packet is dropped.
 151. A node as claimed in claim 144 wherein the node notifies an administrator of the failed access attempt if the packet is dropped.
 152. A node as claimed in claim 144 wherein the node creates a session identifier based on the transformed user identifier, the first key index, the transformed source identifier, and the second key index; encrypts the session identifier using the first key identified by the first key index; generates a hash based on the session identifier; includes the hash in a response packet for transmission to the node originating the received packet; and transmits the response packet to the node originating the received packet.
 153. A computer-readable medium having a computer program executable by a computing device to include data based on at least one of a user identifier and a source identifier in a header of a packet.
 154. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to include the data identifying the user identifier in a sequence number field of the packet.
 155. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to include the data identifying the source identifier in an acknowledgement field of the packet.
 156. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to generate the data in the acknowledgement field with a non-zero value.
 157. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to transform at least one of the user identifier and source identifier to generate the data for inclusion in the header of the packet.
 158. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to transform the user identifier using a cyclic redundancy check (CRC) algorithm.
 159. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to include the transformed user identifier in a sequence number field of the packet.
 160. A computer-readable medium as claimed in claim 159 wherein the computer program is executable by the computing device to append a first key index to the transformed user identifier to generate the data for inclusion in the sequence number field of the packet.
 161. A computer-readable medium as claimed in claim 160 wherein the computer program is executable by the computing device to include the data indicating the transformed source identifier in the acknowledgement field of the packet.
 162. A computer-readable medium as claimed in claim 161 wherein the computer program is executable by the computing device to append a second key index to the transformed source identifier to form the data for inclusion in the acknowledgement field of the packet.
 163. A computer-readable medium as claimed in claim 162 wherein the computer program is executable by the computing device to generate the data included in the acknowledgement field with a non-zero value.
 164. A computer-readable medium as claimed in claim 163 wherein the computer program is executable by the computing device to append a key index to the transformed source identifier to generate the data for inclusion in the acknowledgement field of the packet.
 165. A computer-readable medium as claimed in claim 153 wherein the computer program is executable by the computing device to generate at least one of the user identifier and source identifier with a non-zero value that is included in the acknowledgement field of the header of the packet.
 166. A computer-readable medium as claimed in claim 153 wherein the user identifier indicates a user associated with a source node comprising the computing device, that initiates communication over a network with a destination node by transmitting the packet from the source node to the destination node.
 167. A computer-readable medium as claimed in claim 166 wherein the user identifier comprises a user name of the user.
 168. A computer-readable medium as claimed in claim 166 wherein the source identifier indicates a source node that initiates communication over a network with a destination node by transmitting the packet from the source node to the destination node.
 169. A computer-readable medium as claimed in claim 166 wherein the source identifier is based on a media access control (MAC) address of the source node.
 170. A computer-readable medium as claimed in claim 166 wherein the source node comprises a desktop computer, a laptop computer, personal digital assistant (PDA), or other computing device.
 171. A computer-readable medium as claimed in claim 153 wherein the packet has a transfer control protocol/Internet protocol (TCP/IP) format.
 172. A computer-readable medium as claimed in claim 153 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 173. A computer-readable medium having a computer program for transforming a user identifier; appending a first key index to the user identifier; and including the transformed user identifier and appended first key index in a first field of a header of a packet.
 174. A computer-readable medium as claimed in claim 173 wherein the user identifier comprises a user name of a user of a node initiating communication with another node using the packet.
 175. A computer-readable medium as claimed in claim 173 wherein the user name is subjected to a cyclic redundancy check (CRC) algorithm to generate the transformed user identifier.
 176. A computer-readable medium as claimed in claim 173 wherein the computer program is executed by a node comprising a desktop computer, laptop computer, personal digital assistant (PDA), or other computing device.
 177. A computer-readable medium as claimed in claim 173 wherein the packet is a synchronization (SYN) packet.
 178. A computer-readable medium as claimed in claim 173 wherein the first field comprises a sequence number field.
 179. A computer-readable medium as claimed in claim 173 wherein the computer program is executable by a computing device to transform a source identifier; append a second key index to the source identifier; and include the transformed source identifier and appended second key index in a second field of the packet header.
 180. A computer-readable medium as claimed in claim 179 wherein the source identifier identifies a node initiating communication with another node using the packet.
 181. A computer-readable medium as claimed in claim 179 wherein the source identifier comprises a media access control (MAC) address.
 182. A computer-readable medium as claimed in claim 179 wherein the computer program is executed by a node comprising at least one of a desktop computer, laptop computer, personal digital assistant (PDA), or other computing device.
 183. A computer-readable medium as claimed in claim 179 wherein the source identifier is subjected to a cyclic redundancy check (CRC) algorithm to generate the transformed source identifier.
 184. A computer-readable medium as claimed in claim 179 wherein the packet is a synchronization (SYN) packet.
 185. A computer-readable medium as claimed in claim 179 wherein the second field comprises an acknowledgement field.
 186. A computer-readable medium as claimed in claim 179 wherein the computer program can further be executed to create a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypt the session identifier using a first key identified by the first key index; generate a hash based on the encrypted session identifier; and store at least part of the hash.
 187. A computer-readable medium as claimed in claim 179 wherein the computer program can further be executed to transmit the packet including the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 188. A computer-readable medium as claimed in claim 179 wherein the computer program can further be executed to receive an acknowledgement packet from the destination node in response to the transmitted packet.
 189. A computer-readable medium as claimed in claim 173 wherein the computer program can further be executed by the computing device to extract data from at least one field of the packet; compare data from the packet with the hash; drop the packet if the extracted data and hash fail to match; and continue processing of the packet if the extracted data and the hash match.
 190. A computer-readable medium as claimed in claim 173 wherein the computer program can be executed by the computing device to transmit the packet including the data indicating the transformed user identifier and source identifier from the source node at which the transforming is performed, to a destination node.
 191. A computer-readable medium as claimed in claim 173 wherein the computer program can be executed by the computing device to receive an acknowledgement packet from the destination node in response to the transmitted packet.
 192. A computer-readable medium as claimed in claim 173 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 193. A computer-readable medium having a computer program executable by a computing device to generate a packet with a header having a transformed user identifier, a first key index, a transformed session identifier, and a second key index; create a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypt the session identifier using the first key identified by the first key index; generate a hash based on the session identifier; and store at least part of the hash.
 194. A computer-readable medium as claimed in claim 193 wherein the computer program can be executed by the computing device to transmit the packet including the transformed user identifier and source identifier from a source node comprising the computing device at which the transforming is performed, to a destination node.
 195. A computer-readable medium as claimed in claim 194 wherein the computer program can be executed by the computing device to receive an acknowledgement packet from the destination node in response to the transmitted packet.
 196. A computer-readable medium as claimed in claim 193 wherein the computer program can be executed by the computing device to extract data from the packet, compare data from the packet with the hash, drop the packet if the extracted data and hash fail to match, and continue processing of the packet if the extracted data and the hash match.
 197. A computer-readable medium as claimed in claim 193 wherein the packet is a synchronization (SYN) packet used to initiate communication between source and destination nodes in transfer control protocol/Internet protocol (TCP/IP).
 198. A computer-readable medium having a computer program for extracting data based on at least one of a user identifier and a source identifier from a packet.
 199. A computer-readable medium as claimed in claim 198 wherein the data is extracted from a header of the packet.
 200. A computer-readable medium as claimed in claim 198 wherein the packet is a synchronization (SYN) packet.
 201. A computer-readable medium as claimed in claim 198 wherein the user identifier is derived from a user name of a user originating the packet.
 202. A computer-readable medium as claimed in claim 198 wherein the source identifier is derived from a media access control (MAC) address associated with a node originating the packet.
 203. A computer-readable medium as claimed in claim 198 wherein the data includes a transformed user identifier.
 204. A computer-readable medium as claimed in claim 203 wherein the transformed user identifier is generated with a cyclic redundancy check (CRC) algorithm.
 205. A computer-readable medium as claimed in claim 198 wherein the data includes a transformed source identifier.
 206. A computer-readable medium as claimed in claim 205 wherein the transformed source identifier is generated with a cyclic redundancy check (CRC).
 207. A computer-readable medium as claimed in claim 198 wherein the data extracted from the packet further comprises at least one key index identifying a key.
 208. A computer-readable medium having a computer program executable by a computing device to receive a packet having a transformed user identifier, first key index, transformed source identifier, and second key index; extract a transformed user identifier, first key index, transformed source identifier, and second key index from a packet; create a session identifier based on the transformed user identifier, the first key index, the transformed session identifier, and the second key index; encrypt the session identifier using the first key identified by the first key index; and generate a hash based on the session identifier.
 209. A computer-readable medium as claimed in claim 208 wherein the packet is a synchronization (SYN) packet originating from the computing device of a first node, and received at a computing device of a second node, and the computer program is further executable by the computing device of the second node to include at least part of the hash in a response packet for transmission from the second node to the first node.
 210. A computer-readable medium as claimed in claim 208 wherein the part of the hash comprises the lower sixty-four (64) bits of the hash.
 211. A computer-readable medium as claimed in claim 208 wherein the user identifier is transformed using a cyclic redundancy check (CRC) algorithm.
 212. A computer-readable medium as claimed in claim 208 wherein the encrypting is performed using a DES algorithm.
 213. A computer-readable medium as claimed in claim 208 wherein the hash is generated using a SHA-1 algorithm.
 214. A computer-readable medium having a computer program executable by a node to receive a packet; extract a user identifier and source identifier from the packet; check authorization policy based on the user identifier and source identifier to determine whether the user and source are authorized to pass to a destination indicated by the packet; release the packet if the checking indicates that the packet is permitted by the policy to pass to its destination; and drop the packet if the authorization policy indicates that the packet is not permitted to pass to its destination.
 215. A computer-readable medium as claimed in claim 214 wherein the packet is a synchronization (SYN) packet.
 216. A computer-readable medium as claimed in claim 214 wherein the user identifier is based on a user name of a user of the node originating the packet.
 217. A computer-readable medium as claimed in claim 214 wherein the source identifier is based on a media access control (MAC) address of the node originating the packet.
 218. A computer-readable medium as claimed in claim 214 wherein the source identifier authorization policy is further defined based on a resource indicated by a destination of the packet.
 219. A computer-readable medium as claimed in claim 214 wherein the resource is an application.
 220. A computer-readable medium as claimed in claim 214 wherein the computer program can be executed to create a record of the failed access attempt if the packet is dropped.
 221. A computer-readable medium as claimed in claim 214 wherein the computer program can be executed to notify an administrator of the failed access attempt if the packet is dropped.
 222. A computer-readable medium as claimed in claim 214 wherein the computer program can be executed to create a session identifier based on the transformed user identifier, the first key index, the transformed source identifier, and the second key index; encrypt the session identifier using the first key identified by the first key index; generate a hash based on the session identifier; include the hash in a response packet for transmission to the node originating the received packet; and transmit the response packet to the node originating the received packet. 